TCD scientists have devised a method to predict the impact of global warming on parasitic diseases such as Lyme disease, which is caused by a tick. [Source: http://www.Macleans.ca]

The prediction of which infectious diseases will worsen and which will diminish with rising temperatures is now possible thanks to scientists at TCD.

The method can, the scientists say, identify which infectious diseases will have worsened or diminished effects with rising temperatures.

“Rising temperatures due to global warming can alter the proliferation and severity of infectious diseases, and this has broad implications for conservation and food security,” said Professor Pepin Luijckx, who led the study with William C Campbell, lecturer in parasite biology at TCD and graduate student Devin Kirk.

“It is therefore really important that we understand and identify the diseases that will become more harmful with rising temperatures, with a view to mitigating their impacts,” Prof Luijckx added.

Scientists have found it difficult to pinpoint the the precise impact rising temperature will have on the host and pathogen, and on disease, because temperature can affect these in different ways.

For example, while host immune function and pathogen infectivity may be higher as temperatures rise, pathogen longevity may be lower. Additionally, to predict the severity of disease, scientists need data that doesn’t always exist on the temperature sensitivity of all the processes involved, especially for newly emergent diseases.

Solution

The solution, the TCD scientists say, is that the so-called metabolic theory of ecology can be used to predict how various biological processes respond to temperature. This theory is based on the idea that each process is controlled by enzymes, and that the activity and temperature dependence of these enzymes can be described using simple equations.

Even with limited data, the theory thus allows for the prediction of the temperature dependence of host and pathogen processes.

In their study, the scientists used the water flea and its pathogen and measured how processes such as host mortality, aging, parasite growth and damage done to the host changed over a wide temperature range. They used these measurements to determine the thermal dependencies of each of these processes using metabolic theory.

The results showed that the different processes had unique relationships with temperature. For example, while damage inflicted to the host per pathogen appeared to be independent of temperature, both host mortality and pathogen growth rate were strongly dependent — but in opposite ways.

“What is exciting is that these results demonstrate that linking and integrating metabolic theory within a mathematical model of host-pathogen interactions is effective in describing how and why disease interactions change with global warming,” Prof Luijckx said.

“Due to its simplicity and generality, the method we have developed could be widely applied to understand the likely impact of global warming on a variety of diseases, including diseases affecting aquaculture, such as salmonid diseases like Pancreas disease, pathogens of bee pollinators, such as Nosema, and growth of vector-borne and tick-borne diseases in their invertebrate hosts, such as malaria and Lyme disease,” the Prof concluded.